Bird community energetics in a boreal coniferous forest

The annual minimum energy consumption of the bird community was 2524 × 10 3 kcal km −2 , of which 44% was consumed by wintering species and 73% by passerines. The daily energy consumption was in summer 14–16 × 10 3 and in winter 1–2 × 10 3 kcal km −2 . In spruce forests and in afforested swamps birds required approximately 0.12% of the net primary production. Their total annual energy consumption was covered by invertebrates (59%), vertebrates (2%) and vegetable matter (39%); the food derived from the ground (55%), from trees (44%) and from the air (1%). Arboreal insectivorous passerines, ground passerines and gallinaceous birds were the most important ecological guilds. Among passerines existence metabolism accounted for 73% of the annual energy consumption, extra activity for 17%, breeding activity for 1%, moult for 4% and nestlings for 4%.